Would you please explain one-year vs. three-year rabies vaccines? Is it “paperwork” due to state/county laws and not the strength of the vaccine? Our dog, Cookie, is 15 and in pretty good shape! She’s just now showing age. She had one-year rabies in fall 2011 at a local free clinic — I did not have records of her previous three-year vaccine, so they gave only a one-year vaccine.

If she is still with us next year, does she have to receive another shot? I think that is unreasonable and possibly risky at her age.

Additionally, our vet’s office insists on distemper and Bordetella. I have read that distemper is unnecessary if the dog has had regular vaccinations, and she has — religiously. At this stage of my dog’s life I want the least amount of stress and threat of risks imposed. May I please have your opinion?

Belinda, southern Maryland

In most cases, the difference is strictly clerical. The vaccine itself is usually identical. The duration of validity is based upon local laws.

Please note that the legal validity of a rabies vaccine has nothing whatsoever to do with the vaccine’s effectiveness. Once the government gets involved in anything, all common sense goes out the window. In the case of rabies vaccinations, consistency is markedly absent as well.

Rabies vaccines are legally required for dogs in almost everywhere in the United States for one reason only: Rabies is contagious and deadly to humans. In sub-Saharan Africa, India, and Sri Lanka, rabies is common and tens of thousands of people die from it annually. The overwhelming majority are exposed to the virus by dogs. Therefore, governments in developed countries generally mandate rabies vaccines in dogs. (As a consequence, very few people die of rabies in developed countries, and most of those few are exposed not by dogs but instead by cats, bats, and other animals.)

I therefore strongly agree that rabies vaccines are, in general, a good idea for dogs. If you doubt that, consider the alternative rabies control method that is frequently employed in places such as China and Indonesia: Dogs routinely are poisoned or rounded up and slaughtered by the tens of thousands.

However, the way rabies vaccines are mandated in the United States is generally nonsensical and is certainly not based upon science. Some places them every year in every dog. In many others (which evidently includes Maryland), the first vaccine a dog receives is legally valid for one year and subsequent vaccines are valid for three. Remember that legal validity has nothing to do with the actual immunity elicited by the vaccines, and is only rarely related to the type of vaccine administered. It’s nothing but bureaucratic paperwork. A scientific approach to rabies vaccination would probably result in vaccine intervals of much longer than three years.

In general, rabies vaccination is a good thing for dogs. But overvaccination is not without risk. Vaccines are designed to stimulate the immune system, and some individuals’ immune systems can react aberrantly, leading to complications. I therefore don’t recommend vaccinating any dog — especially a very elderly one — more often than necessary. Some places (such as my home state of California) are starting to display some sense. California recently passed a law that allows rabies vaccine exemptions (with a letter from a licensed veterinarian) for dogs at risk of vaccine complications. Of course, that law is of no use to someone who resides in Maryland.

Belinda, there is a high likelihood that the vaccine your dog received would have been valid for three years if you had presented a previous legally valid certificate of vaccination. If you can dig up an old certificate, you may be able to convince your local authorities to change your dog’s license status. This would enable you to avoid vaccinating her again next year. This is the best option, in my opinion.

Your question about distemper and Bordetella vaccination is very different one from the one about rabies vaccination. Distemper and Bordetella are health threats to dogs but not to people. These are not required by law, and you don’t have to get them if you don’t want them.

After a full puppy series followed by a one-year booster, I do not recommend distemper vaccination any more frequently than every three years. In a 15-year-old dog who has been vaccinated frequently over her life, I don’t usually recommend the vaccine at all. And I’m not a fan of the Bordetella vaccine, either — mainly because it doesn’t really seem to work, and the disease it is supposed to prevent isn’t fatal. I’d recommend that you skip them both.